How to force Storage Foundations disk groups to show up as a resource in Microsoft Cluster Service (MSCS)

I had an issue with an MSCS SQL cluster a while back where the "Volume Manager Disk Group" resource disappeared from the selection drop down! This was not cool as I needed the resource as a dependency of my SQL cluster I was about to setup.

The solution was fairly easy, but most certainly NOT obvious. Here's what you need to do:
Drop to a command prompt and type... (hit enter after each line)
cluster restype "Volume Manager Disk Group" /Delete /TYPE

regsvr32 vxresext.dll

cluster restype "Volume Manager Disk Group" /CREATE /DLL:vxres.dll /TYPE:"Volume Manager Disk Group"

cluster /regext:vxresext.dll

After that's done you should see the resource available in the drop down box. If it matters, this was done on Windows 2003 SP2 R2 x64 Enterprise Edition.